Set preview mode early in Admin::PagesController
Set preview mode early in Admin::PagesController

When running `OnPageLayout` callbacks, it's probably wise to have
`@version` available for choosing draft or public versions of pages
(e.g. when loading a referenced page via the
`Alchemy::Ingredient::Page`).

AlchemyCMS/alchemy_cms,AlchemyCMS/alchemy_cms,AlchemyCMS/alchemy_cms